Name: Why Atlantic fish are invading the Arctic
Uploaded: 2021-05-16T14:26:18.000Z
Duration: 5 min 45 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

As many as half of Earth's species may be

already migrating to escape warming temperatures.

The Arctic ecosystem is particularly vulnerable to invasion.

Scientists aboard this research ship are hunting

the most important fish in the Arctic: polar cod.

Mixed in with the Arctic fish are invaders

The southern species compete for polar cod's food.

So here is a very typical Arctic food web

Polar cod have some of the most impressive

They use a trick that's common among arctic animals,

which also store fat to survive the long winter.

One trawl after another reveals  southern interlopers.

Out of a thousand fish caught in this trawl,

roughly 70% by weight are southern species.

It's hard for the scientists to pinpoint precisely

but that boundary has been slowly creeping northward.

Atlantic waters are saltier and they mostly lack ice.

Atlantic water is as much as seven degrees warmer.

of the Barents Sea, but further north  it's too deep for them.

Meanwhile, the warmer waters bring with them

new species that are shaking up the food web.

Along with new fish, there are Atlantic varieties of copepods.

They store much less fat than copepods native

to the Arctic, making them a less nutritious food source.

That means polar cod may have to spend more energy hunting.

For the same amount of animals that are gonna be eaten,

you don't transfer the same amount of energy.

were among the invaders we just caught in the trawl.

as the polar cod, so we start adding competition

Capelin's not as rich as polar cods, so that goes

or diminishes, then these levels will also be impacted.

in their natural habitat, overfishing and now

rising temperatures have decimated its population.

So here in the Arctic, Atlantic Cod seems like an invader,

but it's also a climate refugee from the south

Historically, most humans who have come to the Arctic

have taken a lot more than data and a few samples.

For at least 45,000 years, people have been coming

Punishing, desolate but rich with resources.

Humans are the Arctic's ultimate apex predator

With countries like Norway extracting fossil fuels offshore,

other sectors are also expanding northward.

From tourism, to shipping, to military operations.

For the animals who, for now, call it home.

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Why Atlantic fish are invading the Arctic

vulnerable

crucial

ultimate

reveal